1. Field of the Invention
This invention relates in general to an automatic control for bilge and sump pumps and in particular to a magnetically actuated float switch for controlling a pump.
2. Description of Related Art
This invention is an improvement on our U.S. Pat. No. 5,297,939 entitled "Automatic Control For Bilge And Sump Pump" which related to the combination of a bilge or sump pump which has a motor mounted in a sealed pump housing and a separate switch housing with a float chamber that communicates with the pump inlet. A magnet is mounted in a float and moves up in the float chamber as the level of the fluid rises. At the top of the float chamber, a one-way valve is mounted so as the liquid level rises, air can pass out the one-way valve so that the water level will rise to allow the magnet to energize a reed switch to start the motor. As the motor starts to pump the water, the water level falls. However, due to the one-way valve in the float chamber, the liquid level in the float chamber does not fall with the level of the water until the liquid level has reached the bottom of the float chamber, at which time air can enter the float chamber and the liquid then passes out of the float chamber, thus allowing the float to move downwardly deactuating the switch. The level in the float chamber remains higher than the liquid level being pumped because of the partial vacuum that is formed in the float chamber above the float which holds the internal liquid above the external liquid level. See also the references cited in our copending patent application Ser. No. 5,297,939.